Micro-Nano Hierarchical Structure From In Situ Functionalized MOFs Enables High-Performance High-Voltage Electrolytes

Ideal solid-state electrolytes (SSEs) should simultaneously possess excellent ionic conductivity, mechanical strength, electrochemical stability, and cathode compatibility. Here, inspired by the hierarchical architecture of organisms like the lotus leaf, a micro-nano hierarchical composite electrolyte was fabricated via in situ growth of a bifunctional metal-organic framework (F&OH-ZIF-8) on a cellulose acetate (CA) substrate. The micro- and nano-sized F&OH-ZIF-8 crystals have the same composition but exhibit different size-dependent advantages. The micro-sized crystals provide greater structural continuity and mechanical support, whereas the nano-sized crystals offer more accessible polar sites and interfacial regions for Li⁺ coordination and transport. Their cooperative integration suppresses dendrite penetration and stabilizes the electrode/electrolyte interphases while facilitating Li⁺ transport. An outstanding SSE with a room-temperature ionic conductivity of 2.9 × 10^-3 S cm^-1, a lithium-ion transference number of 0.61, and a wide electrochemical stability window extending to 5.5 V was obtained by this strategy, resulting in Li||NCM811 full cells achieving a high-capacity retention of 80.9% after 300 cycles at 1C under a high cut-off voltage of 4.6 V. This strategy of transforming existing commercialized ordinary membrane materials into more valuable electrolyte membranes has extremely high practical significance.